Robert Downey Jr. and Jude Law reprise their big-screen turns as Sherlock Holmes and Dr. Watson in this second Guy Ritchie-helmed outing, “Sherlock Holmes: A Game of Shadows.” Once again, this classic, brainy crime-fighting pair are dropped into a noisy world of fistfights, explosions, and slo-mo bullet-time shots. There’s no intellectual pretense in this winter blockbuster, but this sequel at least delivers a smarter story and a better bad guy: Dr. Moriarty, played by Jarred Harris.